There is a wealth of information, misinformation and outright propaganda about fats available - "Saturated fats cause heart attacks", "Margarine is better for you than butter", "Keep your fat intake down to lose weight" and "Keep your fat intake up to give you energy to exercise better". Let's look at what we really need to know.
There are three main ways the body uses fats :
* Structural - Our bodies need fat as a building block. It is incorporated into cell membranes and other body structures, and used in fatty tissue.
* Metabolic - Affects hormones, including prostaglandins which affect metabolism.
* As fuel - It can be burned for energy. In fact, it is the body's preferred source of energy.
As well as that, fats are a valuable source of micronutrients, some of which can't be obtained from other foods.
So it is very important to eat enough fat, but also to make sure we eat the right kinds of fats. The wrong ones can have a profound effect on many body functions. There are two main debates about fat - how much we should eat, and which kinds we should eat. Let's look first at the different types of fat.
There are several different ways of defining fats:
* Degree of saturation - saturated, monounsaturated and polyunsaturated. This is the main way that people differentiate fats and we'll go into that in more depth shortly.
* Animal fats vs vegetable oils. This largely ties in with degree of saturation, with animal fats and tropical oils being mostly saturated, and vegetable oils being mostly unsaturated.
* Chain length. Short and medium chain fatty acids are found in butterfat and tropical oils, have anti-microbial & immune enhancing properties and are easily absorbed for energy, making them less likely to cause weight gain. This is why MCT (or Medium Chain Triglycerides) are often used in sports supplements. Unsaturated fats are generally made up of long or very long chain fatty acids.
* Cis form vs Trans form. In nature, most fats occur in a "cis" form. In this form, they "fit" the fat receptors in our body, and can be utilised. Modern processing methods (including heating, hydrogenation, bleaching & deodorising) turn cis fats into trans fats, which no longer fit. Our body still tries to use them, but they don't do the job properly and disrupt your cellular metabolism, resulting in a variety of health hazards.
Saturated Fats
Saturated fats are straight chains of carbon and hydrogen that pack together easily so that they are relatively solid at room temperature. They are found predominantly in animal products and tropical oils.
Fats in general, and saturated fats in particular, have been widely vilified by health authorities and nutritionists since the introduction of the Lipid Hypothesis in the 1950's. This stated that heart disease was caused by high intakes of saturated fats and that changing to polyunsaturates would improve your health. Fats have also been blamed for obesity and many other diseases, and low fat foods abound. Many people will tell you that a low fat diet is the healthiest.
But when we look at the facts we find that much of this is unfounded. Weston Price, in his studies of healthy people eating their traditional diets, found that all included high levels of saturated fats. All of the societies understood the importance of getting enough fats in their diet and sought them out as much as possible. The foods eaten included unpasteurised dairy products, eggs, meats and organ meats and seafood, and the fatty portions were the most prized.
A look at some cookbooks from the late 1800's show that our recent ancestors, while not eating a wholly traditional diet, were also eating diets that were high in saturated fats. Diseases like cancer and heart disease were rare up until the early parts of the 20th century. As our saturated fat intake decreased and our polyunsaturated fat intake increased, the prevalence of these and other degenerative diseases also increased. Obesity is rife, despite the rate at which low fat products fly off the shelves. The lipid hypothesis seems to be wrong.
You may be thinking "What about all the studies that prove saturated fats cause heart disease?". In fact, many of these studies were done using hydrogenated polyunsaturates, not saturated fats at all. Many other studies have shown that those with the highest levels of saturated fat intake had the better health. And many other studies were inconclusive due to the many other factors involved.
Saturated fats are needed for many of our bodily processes. Just some of them are:
* They are needed to maintain cell membranes, which are at least 50% saturated fat, giving them stiffness and integrity.
* They keep our bones strong and healthy by allowing calcium to be incorporated into them. This requires >50% of dietary fat to be saturated.
* They lower Lp(a) a substance in the blood that indicates proneness towards heart disease
* They enhance the immune system
* They aid in utilisation of essential fatty acids, and help to retain omega 3’s in the tissues
* Short & medium chain fatty acids have anti-microbial properties and protect against harmful micro-organisms in the digestive tract
But what about cholesterol levels? We are often told that eating saturated fats increases cholesterol levels. Well, first of all, that hasn't been satisfactorily proven. It has been suggested that the reason that blood cholesterol levels drop when saturated fats are replaced by polyunsaturates is to do with the integrity of the cell membranes. When polyunsaturates are incorporated into their structure they become limp. To regain their stiffness, they must rob cholesterol from the blood, temporarily lowering the amount stored there. And secondly, there is now some doubt as to whether cholesterol levels are an accurate indicator of your likelihood of getting heart disease. Cholesterol is another substance that is vital to your body's health, and is made by the liver as needed. For more information on cholesterol, visit the Cholesterol and Health website.
So it seems that there is nothing inherently bad in saturated fats. In their natural states, as part of a whole food and part of a varied diet, they are balanced and nutritious. It is when they are processed that problems arise.
* Pasteurising milk, for example, destroys the beneficial enzymes needed to assimilate it's nutrients, which could be why many people are dairy intolerant. It also explains why people frequently get osteoporosis despite being milk drinkers - they are unable to utilise the calcium.
* Homogenisation of milk strains the fat particles of the cream through tiny pores under pressure. This makes the fat particles very small so that they stay suspended in the milk. Sadly, the once highly nutritious fat is now more likely to be rancid and oxidised. This process has been linked to heart disease by some researchers.
* Low fat dairy products have been stripped of many of their fat soluble vitamins, and should be avoided.
* Powdered eggs and milk have had their cholesterol oxidised by the processing.
* Smoked and processed meats often have rancid fats caused by the processing.
We are all different and need different amounts of saturated fats. But there is no need to avoid them, cut every bit of fat off your meat, or seek out low fat products. A good rule of thumb is : If it's a whole food, properly prepared, eat it. If it's been tampered with (processed), don't.
Monounsaturated Fats
Monounsaturated fats have one double carbon bond, which means they are missing two hydrogen atoms. They are usually liquid at room temperature, but solidify when refrigerated. They are quite stable. They are mostly found in olives, nuts and avocados.
These types of fats don't seem to be subject to the same level of dissention as saturates. It seems to be generally agreed that these are a healthful form of fat. One caveat though - eaten to excess, they can cause weight gain. This is because they are longer chain and not as easily converted to energy as short or medium chain fats. But some extra virgin olive oil on a salad, a small handful of correctly prepared nuts, or some avocado dip with vegetables are all nutritious, tasty foods.
Polyunsaturated Fats
Polyunsaturated fatty acids come mostly from oils extracted from seeds. Their molecules have kinks in them at the point of the unsaturated double bonds. They do not pack together easily and therefore tend to be liquid at room temperature. These oils are extremely unstable and go rancid very easily.
One very important category of polyunsaturated oils are the essential fatty acids or EFAs. They are called essential because they can't be made by the body, so must come from the diet. They are:
* Linoleic acid, an Omega-6 oil - present in large quantities in most vegetable oils, and in smaller quantities in animal and tropical oils.
* Alpha-Linolenic acid, an Omega-3 oil - flaxseed is considered the best source of it. There are also smaller quantities in hemp, canola and soybean oils, and in some animal fats, depending on the feed. It is far less readily available than Omega-6.
These essential fatty acids are also used by the body to make other fatty acids.
* Linoleic acid (Omega-6) is used to make Gamma-Linolenic acid, which is also found in evening primrose, blackcurrant & borage oils.
* Alpha-linolenic acid (Omega-3) is used to make Eicosapentanoic acid (EPA) and Docosahexanoic acid (DHA). But some people lack the enzymes to make the conversion. This is especially common amongst people whose ancestors ate a lot of oily fish. These two acids are abundant in fish oils, and it seems that their bodies lost the ability to convert the acids as they didn't need to. So for some people, it is also necessary to eat fatty fish like salmon, sardines or mackerel on a regular basis, or to supplement with fish oil.
Maybe it is because some polyunsaturates are essential, that it was hypothesised that more is better, leading to the dramatic increase in their consumption that was seen during the 20th century. But Weston Price found that only small amounts were eaten in traditional diets, and there has been no evidence that more is better. In fact, there are a number of dangers associated with excess consumption of polyunsaturated oils, especially Omega-6.
It is generally agreed that Omega-6 and Omega-3 fatty acids are needed in balance. Some researchers are now saying that the ideal ration is 1:1, but the intake of Omega-6 is much higher than Omega-3 in the average diet. This is because Omega-6 is so much more prevalent in the vegetable oils that are frequently eaten. So the first danger of excess consumption is that if the ratio is wrong, it can stop the Omega-3 fatty acids from being absorbed.
Further, many studies have shown that increased consumption of polyunsaturates correlates with high incidences of cancer, heart disease, immune system dysfunction, damage to liver, lungs & reproductive organs, depressed learning ability, impaired growth, obesity.
And the news doesn't get better. These types of oils go rancid very easily. Unless they are expeller pressed or cold pressed, they are likely to be rancid, oxidized or chemically tainted before they are even bottled, with high levels of free radicals. If they are used for cooking, more free radicals will be created. Among other things, free radicals are associated with wrinkles and premature aging, tumours, plaque in the blood, autoimmune diseases.
And as if that isn't bad enough, they are often made into margarines by hydrogenation. This process creates trans fats which block absorption of EFAs, increase blood cholesterol, paralyse the immune system, are associated with cancer, atherosclerosis, diabetes, obesity and problems with bones and tendons, are also associated with sterility, birth defects, low birth weight babies & difficulty in lactation.
These are the dangers associated with eating too much polyunsaturated fat, eating the wrong ratio of Omega-6 to Omega-3 or eating oils that have been badly processed or hydrogenated. But that doesn't mean you have to avoid all polyunsaturated fats. Small amounts of certain oils, that have been cold pressed and carefully stored, is recommended. Flaxseed is a important source of Omega-3 fatty acids which most people can benefit from, either freshly ground or in oil form. Remember that flaxseed oil should always be stored in the fridge in an opaque bottle.
How much fat do we need?
Everybody has a different opinion here. Some low fat diets recommend as little as sub 20% of calories, the Zone diet recommends 30% of calories, whereas some high protein diets are much higher. Weston Price found that the traditional diets he studied derived 30% to 80% of their calories from fat, with only 5% of calories coming from polyunsaturated oils.
The truth is - it all depends on our own individual metabolism. If you are a Hunter-Gatherer or Protein type, you will likely need a higher level of fat, and a higher proportion of saturated fats. If you are an Agriculturist or Carbo type, you will need less overall fat, and may need slightly less saturated fat, and a little more unsaturated. But aim to keep Onega-3 and Omega-6 intakes about even and don't eat more than about 5% of your calories in polyunsaturates.
The first thing to do is to get rid of the bad fats in your diet, and replace them with good ones. See the next post about it. Eat a level of fat in line with whatever your chosen diet plan is. Then adjust to suit. If you are feeling hungry between meals, eat more fat. If you eat what seems like a fatty meal and feel a little sick, then reduce the fat or try a different type of fat. Some types of fat may suit you better than others. The last thing to remember is that you may have food sensitivities that need to be taken into account.
More: Good Fats or Bad Fats, Macronutrients. Carbohydrates, Macronutrients. Protein
